What's a Diagnosis All About?

By Robert Mootz, DC

In school, we were taught the importance of figuring out what was wrong with the patient before we started trying to fix it. Perhaps one of the biggest failings in clinical management is the "hammer and nails" phenomenon.

If you are a surgeon, you frequently may find something on which to operate, yet if you are a chiropractor, you may find something on the same patient that needs adjustment. And there is no shortage of technological advancement in diagnosis, bringing new devices and refinements to practitioners to "better" evaluate the patient and provide justification for applying your "hammer" to the "nails" you see in the patient.

Of course, the advancements that come to the market come at a high cost. Unlike in the rest of the high-tech world, where advancement usually equates to more zip for fewer bucks, the latest and greatest medical advancements frequently come at quite a premium. It's not a surprise that policy-makers and health service researchers have been taking a much more systematic approach by looking at the effectiveness, utility and value of existing and emerging diagnostic tests.

What's the drill? First and foremost, safety is always the key issue in technology assessments of diagnostic tests. Does the procedure put the patient at any risk? How does that risk stack up to the risks of alternative diagnostic procedures? Also, what has become increasingly common in technology assessment circles is something not previously considered as a safety issue: How will information gained from a test be used to make care decisions, and will those care decisions put the patient at risk?

In other words, downstream impacts on the patient's well-being as a result of performing a diagnostic test are entering the discussions about whether a test is worth it. For example, we know anatomical findings of MRI or discography images frequently form the basis for spine surgery decisions. However, the results of these surgical outcomes vary greatly. They can either be better or perhaps even worse than the outcome of pursuing a conservative option. Conventional wisdom often held that more diagnostic information is always a good thing and that making the choices about interventions is really where the action is - clinically speaking and from a policy angle.

The new trend has been to ask questions such as: "Would it be in the patient's best interest if we make it easy and profitable to pay for diagnostic tests (such as advanced imaging) that offer anatomical findings upon which to base care decisions (such as surgery)?" And: "Would it be better for the patient if we were to make it easier to obtain more functional rehab care before performing imaging?" Yep. I've actually heard payers and policy-makers having those discussions.

To find the answers, policy-makers are turning to the scientific evidence to more critically assess not only safety data, which is quite scarce, but also accuracy data. We all learned that a diagnostic test should have high reliability, including good test-retest measurements, as well as high scores on intrarater and interrater reliability. This kind of information about a diagnostic test usually is fairly straightforward and cheap to obtain, and the information usually is available. But what is more important is that what used to be called "validity" is now often framed as diagnostic accuracy.

Accuracy is a more difficult thing to assess because it entails comparing results of a test to a "gold standard" and other comparison diagnostics. Frequently, diagnostics that have become standard have become so in the absence of gold (or even bronze) standards. Rather, their diffusion into the culture of practice norms drives what is done. Orthopedic tests, anyone?

Beyond policy-makers searching for more information on test validity and accuracy, even harder questions are being asked: What is the diagnostic impact compared to other available diagnostic tests? Does a given test help narrow the differential diagnosis in a clinically meaningful way? Does it actually reduce the need for further diagnostic testing?

And what about the therapeutic impact I alluded to earlier? Does performing a diagnostic test increase the likelihood of a patient receiving a more effective and definitive intervention? Does having the test speed up recovery or prolong it? And perhaps even more significant, is having the information from a particular diagnostic test actually predictive of what the patient's ultimate outcome is going to be?

In the past, these were not the typical kinds of research questions new diagnostic interventions confronted. However, today, these questions are critically important and difficult to deal with in case management. They are the questions all of us wrestle with in many of the patients we care for, and these kinds of questions need to be answered before one can even start to assess the cost side of the equation.

For us chiropractors, diagnostic imaging and new ways to assess nerve and muscle activity are emerging, and are the most probable procedures within our purview to receive such scrutiny. For example, the kinds of research questions that the latest spine-imaging technology will need to address may include accuracy compared to existing options for evaluating degenerative spondylolisthesis and instability, suspected spinal stenosis, radicular pain, and nonspecific spine pain. What is the reliability of the test for these clinical situations? How about the effect on the need for further diagnostic tests (discography, nerve conduction, etc.)? Or the effect on the treatment received, efficacy of moving from a diagnosis into an effective treatment, and the outcomes of test-directed treatment?

Of course, if you are a patient considering highly invasive and expensive medical interventions for which your recovery and disability (or lack thereof) are at stake, you would want to have the answers to all of these things before submitting your body, bank account and/or insurance policy. But as a doctor or vendor, there will be more challenges in sorting through all of the decision-making and development of tests.

Overall, these are the kinds of questions evidence and research need to address. The pragmatics and challenges in fostering innovation and advancement, while reducing ineffective or harmful care, likely will become even greater in the future.